Costa Rica watches lots of US television - but is it stealing those cable signals?

United States television executives are shouting ''cable piracy'' at this Central America nation. And Costa Rica is hissing ''cultural imperialism'' back at the United States.

Ever since Cable Color, S. A., started beaming 13 cable television channels from the US into an estimated 5,000 Costa Rican homes three years ago, a complex legal, political, and cultural debate has been building over television.

One issue is whether Cable Color, a Costa Rican corporation, can legally pick up and a make profit on cable signals for which US cable operators say it is not paying a usage fee.

Spokesmen for Home Box Office, the movie and performance channel available to cable viewers here, say they have no Costa Rican subscribers - yet Cable Color charges about $10 a month for reception of the channel.

Cable Color's general manager says the company pays a commission to a cable distributor in Los Angeles. But both Cable News Network and Home Box Office, two of the 13 channels distributed here, say they have no contracts and receive no payment.

The serious local concern is how slick, consumer-oriented US television will affect Costa Rica in the long run. Many scholars, sociologists, and politicians worry that a flood of North American influence will dilute native culture and make Costa Ricans identify more with the US than with their own country.

''The values of industrialized society - consumerism and high technology - don't apply here,'' says Francisco Escobar, an award-winning Costa Rican novelist. Cable TV, on top of the already heavy US influence in Costa Rica, will lead to loss of cultural identity in Costa Ricans, Mr. Escobar says. He says they are already ''culturally confused.''

Critics also point out that because cable TV's advertising pushes US fashion, music, and other products, third-world businesses and economies will suffer.

Laws governing telecommunications are outdated. But international telecommunications pacts state that transmission, not reception, of satellite signals must be controlled - and therefore anyone who picks up cable signals is not technically breaking the law. But the director of international sales for the company that generates Cable Network News says Costa Rica signed the International Copyright Treaty, and holds that movie and program rights are subject to international copyright fees.